In recent years, the former internal documents of the tobacco industry have been investigated in regard to secret alliances between several prominent representatives of the medical profession and public health sciences in Germany. For the German occupational medicine, however, there exist only sparse investigations for this issue. There is a strong need of information to investigate which disreputable role the hidden cooperation between the occupational medicine and the tobacco industry has taken place in Germany. Since 1970, the scientific research about harmful effects of passive smoking was at the top of the agenda for the tobacco industry. In the tobacco industry documents can be found plenty of solid evidence that prominent representatives of the German occupational medicine have supported the tobacco industry for many years in their efforts to deny the harmful effects of passive smoking. This took place for example in scientific conferences, which have been sponsored and secretly directed by the tobacco industry, and as well by scientific publications about the harmful effects of passive smoking, which have been requested by the tobacco industry. Furthermore, the German Association of the Tobacco Industry (VdC) secretly financed many studies, which were carried out exclusively by scientists, among them many occupational physicians, who had tight links to the tobacco industry. Fortunately, a discussion about the dangerous cooperation between scientists and the tobacco industry has been initiated in Germany in recent years. The first medical association, which approved an ethical codex not to cooperate with the tobacco industry in 2006, was the German Association for Pneumology and Respiration Medicine (DGP). This codex included the denial of any financial resources from the tobacco industry for research projects, consulting activities, fees for presentations and travel expenses. It would be desirable that further universities, research institutions, medical faculties and scientific associations would follow this positive example.